Feeding and related morphology of salivary glands of Bradysia odoriphaga (Diptera: Sciaridae)

The amount of Bradysia odoriphaga larval feeding at each developmental stage and the related morphology of salivary glands were investigated in this study. The amount of daily feeding in the third instar was greatest among all the developmental stages while the amount of cumulative feeding in the fourth-instar accounted for 53.56% of the total amount of larval feeding. The daily amount of feeding by B. odoriphaga during the whole larval stage peaked in the 8th and 14th day after hatching. The paired and transparent salivary glands of B. odoriphaga were characterized by two distinct regions: an anterior region and a posterior region. At the fourth-instar and pupal stage, the length of salivary glands decreased significantly compared with that of the third-instar, and the integrity of epithelium cytoplasm in the salivary glands also decreased markedly because of the formation of cytoplasmic vacuoles and degradation of rough endoplasmic reticulum and mitochondria. We concluded that the decrease of daily feeding amount in the last instar was related to the structural change of salivary gland closely. The function of salivary glands in B. odoriphaga was mainly secretion of silk and cocooning-like materials during the last larval instar.